| /* Sequential list data type implemented by a hash table with a binary tree. |
| Copyright (C) 2006-2007, 2009-2020 Free Software Foundation, Inc. |
| Written by Bruno Haible <bruno@clisp.org>, 2006. |
| |
| This program is free software: you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 3 of the License, or |
| (at your option) any later version. |
| |
| This program is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| GNU General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with this program. If not, see <https://www.gnu.org/licenses/>. */ |
| |
| /* Common code of gl_avltreehash_list.c and gl_rbtreehash_list.c. */ |
| |
| /* Hash table entry representing the same value at more than one position. */ |
| struct gl_multiple_nodes |
| { |
| struct gl_hash_entry h; /* hash table entry fields; must be first */ |
| void *magic; /* used to distinguish from single node */ |
| gl_oset_t nodes; /* set of nodes, sorted by position */ |
| }; |
| /* A value that cannot occur at the corresponding field (->left) in |
| gl_list_node_impl. */ |
| #define MULTIPLE_NODES_MAGIC (void *) -1 |
| |
| /* Returns the position of the given node in the tree. */ |
| static size_t |
| node_position (gl_list_node_t node) |
| { |
| size_t position = 0; |
| |
| if (node->left != NULL) |
| position += node->left->branch_size; |
| for (;;) |
| { |
| gl_list_node_t parent = node->parent; |
| |
| if (parent == NULL) |
| return position; |
| /* position is now relative to the subtree of node. */ |
| if (parent->right == node) |
| { |
| position += 1; |
| if (parent->left != NULL) |
| position += parent->left->branch_size; |
| } |
| /* position is now relative to the subtree of parent. */ |
| node = parent; |
| } |
| } |
| |
| /* Compares two nodes by their position in the tree. */ |
| static int |
| compare_by_position (const void *x1, const void *x2) |
| { |
| gl_list_node_t node1 = (gl_list_node_t) x1; |
| gl_list_node_t node2 = (gl_list_node_t) x2; |
| size_t position1 = node_position (node1); |
| size_t position2 = node_position (node2); |
| |
| return (position1 > position2 ? 1 : |
| position1 < position2 ? -1 : 0); |
| } |
| |
| /* Compares a node's position in the tree with a given threshold. */ |
| static bool |
| compare_position_threshold (const void *x, const void *threshold) |
| { |
| gl_list_node_t node = (gl_list_node_t) x; |
| size_t position = node_position (node); |
| return (position >= (uintptr_t)threshold); |
| } |
| |
| /* Returns the first element of a non-empty ordered set of nodes. */ |
| static gl_list_node_t |
| gl_oset_first (gl_oset_t set) |
| { |
| gl_oset_iterator_t iter = gl_oset_iterator (set); |
| const void *first; |
| |
| if (!gl_oset_iterator_next (&iter, &first)) |
| abort (); |
| gl_oset_iterator_free (&iter); |
| return (gl_list_node_t) first; |
| } |
| |
| /* Adds a node to the hash table structure. |
| If duplicates are allowed, this function performs in average time |
| O((log n)^2): gl_oset_nx_add may need to add an element to an ordered set |
| of size O(n), needing O(log n) comparison function calls. The comparison |
| function is compare_by_position, which is O(log n) worst-case. |
| If duplicates are forbidden, this function is O(1). |
| Return 0 upon success, -1 upon out-of-memory. */ |
| static int |
| add_to_bucket (gl_list_t list, gl_list_node_t new_node) |
| { |
| size_t bucket = new_node->h.hashcode % list->table_size; |
| |
| /* If no duplicates are allowed, multiple nodes are not needed. */ |
| if (list->base.allow_duplicates) |
| { |
| size_t hashcode = new_node->h.hashcode; |
| const void *value = new_node->value; |
| gl_listelement_equals_fn equals = list->base.equals_fn; |
| gl_hash_entry_t *entryp; |
| |
| for (entryp = &list->table[bucket]; *entryp != NULL; entryp = &(*entryp)->hash_next) |
| { |
| gl_hash_entry_t entry = *entryp; |
| |
| if (entry->hashcode == hashcode) |
| { |
| if (((struct gl_multiple_nodes *) entry)->magic == MULTIPLE_NODES_MAGIC) |
| { |
| /* An entry representing multiple nodes. */ |
| gl_oset_t nodes = ((struct gl_multiple_nodes *) entry)->nodes; |
| /* Only the first node is interesting. */ |
| gl_list_node_t node = gl_oset_first (nodes); |
| if (equals != NULL ? equals (value, node->value) : value == node->value) |
| { |
| /* Found already multiple nodes with the same value. |
| Add the new_node to it. */ |
| return gl_oset_nx_add (nodes, new_node); |
| } |
| } |
| else |
| { |
| /* An entry representing a single node. */ |
| gl_list_node_t node = (struct gl_list_node_impl *) entry; |
| if (equals != NULL ? equals (value, node->value) : value == node->value) |
| { |
| /* Found already a node with the same value. Turn it |
| into an ordered set, and add new_node to it. */ |
| gl_oset_t nodes; |
| struct gl_multiple_nodes *multi_entry; |
| |
| nodes = |
| gl_oset_nx_create_empty (OSET_TREE_FLAVOR, |
| compare_by_position, NULL); |
| if (nodes == NULL) |
| return -1; |
| |
| if (gl_oset_nx_add (nodes, node) < 0) |
| goto fail; |
| if (gl_oset_nx_add (nodes, new_node) < 0) |
| goto fail; |
| |
| multi_entry = |
| (struct gl_multiple_nodes *) malloc (sizeof (struct gl_multiple_nodes)); |
| if (multi_entry == NULL) |
| goto fail; |
| multi_entry->h.hash_next = entry->hash_next; |
| multi_entry->h.hashcode = entry->hashcode; |
| multi_entry->magic = MULTIPLE_NODES_MAGIC; |
| multi_entry->nodes = nodes; |
| *entryp = &multi_entry->h; |
| return 0; |
| |
| fail: |
| gl_oset_free (nodes); |
| return -1; |
| } |
| } |
| } |
| } |
| } |
| /* If no duplicates are allowed, multiple nodes are not needed. */ |
| new_node->h.hash_next = list->table[bucket]; |
| list->table[bucket] = &new_node->h; |
| return 0; |
| } |
| /* Tell GCC that the likely return value is 0. */ |
| #define add_to_bucket(list,node) \ |
| __builtin_expect ((add_to_bucket) (list, node), 0) |
| |
| /* Removes a node from the hash table structure. |
| If duplicates are allowed, this function performs in average time |
| O((log n)^2): gl_oset_remove may need to remove an element from an ordered |
| set of size O(n), needing O(log n) comparison function calls. The |
| comparison function is compare_by_position, which is O(log n) worst-case. |
| If duplicates are forbidden, this function is O(1) on average. */ |
| static void |
| remove_from_bucket (gl_list_t list, gl_list_node_t old_node) |
| { |
| size_t bucket = old_node->h.hashcode % list->table_size; |
| |
| if (list->base.allow_duplicates) |
| { |
| size_t hashcode = old_node->h.hashcode; |
| const void *value = old_node->value; |
| gl_listelement_equals_fn equals = list->base.equals_fn; |
| gl_hash_entry_t *entryp; |
| |
| for (entryp = &list->table[bucket]; ; entryp = &(*entryp)->hash_next) |
| { |
| gl_hash_entry_t entry = *entryp; |
| |
| if (entry == &old_node->h) |
| { |
| /* Found old_node as a single node in the bucket. Remove it. */ |
| *entryp = old_node->h.hash_next; |
| break; |
| } |
| if (entry == NULL) |
| /* node is not in the right bucket. Did the hash codes |
| change inadvertently? */ |
| abort (); |
| if (((struct gl_multiple_nodes *) entry)->magic == MULTIPLE_NODES_MAGIC |
| && entry->hashcode == hashcode) |
| { |
| /* An entry representing multiple nodes. */ |
| gl_oset_t nodes = ((struct gl_multiple_nodes *) entry)->nodes; |
| /* Only the first node is interesting. */ |
| gl_list_node_t node = gl_oset_first (nodes); |
| if (equals != NULL ? equals (value, node->value) : value == node->value) |
| { |
| /* Found multiple nodes with the same value. |
| old_node must be one of them. Remove it. */ |
| if (!gl_oset_remove (nodes, old_node)) |
| abort (); |
| if (gl_oset_size (nodes) == 1) |
| { |
| /* Replace a one-element set with a single node. */ |
| node = gl_oset_first (nodes); |
| node->h.hash_next = entry->hash_next; |
| *entryp = &node->h; |
| gl_oset_free (nodes); |
| free (entry); |
| } |
| break; |
| } |
| } |
| } |
| } |
| else |
| { |
| /* If no duplicates are allowed, multiple nodes are not needed. */ |
| gl_hash_entry_t *entryp; |
| |
| for (entryp = &list->table[bucket]; ; entryp = &(*entryp)->hash_next) |
| { |
| if (*entryp == &old_node->h) |
| { |
| *entryp = old_node->h.hash_next; |
| break; |
| } |
| if (*entryp == NULL) |
| /* node is not in the right bucket. Did the hash codes |
| change inadvertently? */ |
| abort (); |
| } |
| } |
| } |
| |
| /* Builds up the hash table during initialization: Stores all the nodes of |
| list->root in the hash table. |
| Returns 0 upon success, -1 upon out-of-memory. */ |
| static int |
| add_nodes_to_buckets (gl_list_t list) |
| { |
| /* Iterate across all nodes. */ |
| gl_list_node_t node = list->root; |
| iterstack_t stack; |
| iterstack_item_t *stack_ptr = &stack[0]; |
| |
| for (;;) |
| { |
| /* Descend on left branch. */ |
| for (;;) |
| { |
| if (node == NULL) |
| break; |
| stack_ptr->node = node; |
| stack_ptr->rightp = false; |
| node = node->left; |
| stack_ptr++; |
| } |
| /* Climb up again. */ |
| for (;;) |
| { |
| if (stack_ptr == &stack[0]) |
| goto done; |
| stack_ptr--; |
| if (!stack_ptr->rightp) |
| break; |
| } |
| node = stack_ptr->node; |
| /* Add the current node to the hash table. */ |
| node->h.hashcode = |
| (list->base.hashcode_fn != NULL |
| ? list->base.hashcode_fn (node->value) |
| : (size_t)(uintptr_t) node->value); |
| if (add_to_bucket (list, node) < 0) |
| goto fail; |
| /* Descend on right branch. */ |
| stack_ptr->rightp = true; |
| node = node->right; |
| stack_ptr++; |
| } |
| done: |
| return 0; |
| |
| fail: |
| /* Undo everything. */ |
| for (;;) |
| { |
| /* Descend on left branch. */ |
| stack_ptr->rightp = false; |
| node = node->left; |
| stack_ptr++; |
| /* Descend on right branch. */ |
| for (;;) |
| { |
| if (node == NULL) |
| break; |
| stack_ptr->node = node; |
| stack_ptr->rightp = true; |
| node = node->right; |
| stack_ptr++; |
| } |
| /* Climb up again. */ |
| for (;;) |
| { |
| if (stack_ptr == &stack[0]) |
| goto fail_done; |
| stack_ptr--; |
| if (stack_ptr->rightp) |
| break; |
| } |
| node = stack_ptr->node; |
| /* Remove the current node from the hash table. */ |
| remove_from_bucket (list, node); |
| } |
| fail_done: |
| return -1; |
| } |
| /* Tell GCC that the likely return value is 0. */ |
| #if __GNUC__ >= 3 |
| # define add_nodes_to_buckets(list) \ |
| __builtin_expect ((add_nodes_to_buckets) (list), 0) |
| #endif |
